Forensic Science Study Guide Chapter 6 Name:______

1. Why are fibers considered class evidence?

They can’t be traced back to an individual.

2. Fabric is made of __fibers______. Fibers are made of twisted ___filaments______.

3. What are the 2 type of fibers and fabric?

Natural, artificial

4. Name 6 types of synthetic fibers:

Rayon,, Acetate, Acrylic, ,

5. Name 5 types of natural fibers:

Silk, , , , Cashmere

6. Natural fibers are classified according to their __origin______:

a. Vegetable or cellulose

b. Animal or protein

c. Mineral

7. Cellulose fibers:

Cotton—vegetable ; strong, tough, flexible, moisture-absorbent, not shape-retentive

Rayon—chemically altered cellulose; soft, lustrous, versatile

Cellulose acetate—cellulose that is chemically altered to create an entirely new compound not found in nature

8. Protein fibers:

Wool—animal fiber coming most often from sheep, but may be goat (mohair), (angora), , , , or vicuña

Forensic Science Study Guide Chapter 6 Fibers Name:______

Silk______—insect fiber that is spun by a silkworm to make its cocoon; the fiber reflects light and has insulating properties

9. Mineral Fibers:

a. —a that has been used in fire-resistant substances

b. Rock wool—a manufactured mineral fiber

c. Fiberglass—a manufactured inorganic fiber

10. Synthetic Fibers : Made from derivatives of petroleum, coal, and natural gas.

11. a. Nylon—most durable of man-made fibers; extremely lightweight

b. Polyester—most widely used man-made fiber

c. Acrylic—provides warmth from a lightweight, soft, and resilient fiber

d. Spandex—extreme elastic properties

12. Weave terminology:

Yarn—a continuous strand of fibers or filaments that may be twisted together

Warp—lengthwise yarn

Weft—crosswise yarn

Blend—a fabric made up of two or more different types of fibers

13. Weave Patterns:

a. Plain

Forensic Science Study Guide Chapter 6 Fibers Name:______

b. Satin

c. Twill

14. Which weave is the most common pattern?

Plain weave

15. Which design resembles a stair steps?

Twill

16. Denim is an example of what weave pattern?

Twill

17. In which weave pattern does the warp yarn is pass over one to three weft yarns before going under One? Twill

18. ____Knitting______are made by interlocking loops into a specific arrangement. It may be continuous thread or a combination.

Forensic Science Study Guide Chapter 6 Fibers Name:______

19. Synthetic fibers are made of polymers, which are long chains of repeating chemical units.

20. The word __polymer______means many units.

21. Filament Cross Sections:

R ound 4-

Octalobal T rilobal Irregular

Dogbone or Multi- Dumbbell or 21.

22. Testing for identification: a. Density______—the mass of an object divided by the volume of the object b. Refractive index—measurement of the bending of light as it passes from air into a solid or liquid c. Fluorescence—absorption and reemission of light; used for comparing fibers as well as spotting fibers for collection

Forensic Science Study Guide Chapter 6 Fibers Name:______

23. There are more than 7,000______different dye formulations.

24. Chromatography is used to separate dyes for comparative analysis.

25. Collection of fiber evidence:

Bag clothing items individually in paper bags. Make sure that different items are, are not placed on the same surface before being bagged.

Make tape lifts of exposed skin areas and any inanimate objects.

Removed fibers should be folded into a small sheet of paper and stored in a paper bag.

26. Wayne Williams was convicted in 1982 based on ___carpet Fibers______that were found in his home, in his car, and on several murder victims.